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IQ)- —> <— iQl — □=] !□ □ CH iQi 



LIGHTNING 

AND 

Petroleum Storage Tanks 


a 

0 
























































































































































A FOREWORD 

TO THE PETROLEUM INDUSTRY 

There would be no tank fires if you knew how to prevent them, 
would there? 

This little book will tell you why your tanks take fire during 
thunder storms and how to prevent these fires. 

The lessons taught in this booklet are established on funda¬ 
mental truths and should be scientifically discussed by all who are 
interested, for the national welfare. 

The principles enumerated are the essence of years of observa¬ 
tion in the field and of scientific research in the laboratory and are 
based on unassailable facts. 

Hang up the booklet in your office. Some day you will want it. 



Made in Oklahoma 

©Cl. A5977U 5 


/ 


SEP 13 !9?C 











SIX SCIENTIFIC MAXIMS RELATIVE TO LIGHTNING 
PAUSE A MINUTE WITH EACH 


ONE 

Lightning results from previous electrical conditions and can 
not occur without these previous electrical conditions. 

TWO 

Lightning can only occur in an electrical resisting medium such 
as air, wood, etc., but never on a good and sufficient electrical con¬ 
ductor. 

THREE 

Lightning can not occur within a metallic structure such as a 
railway train or a steel structural building or a petroleum storage 
tank. 

FOUR 

Lightning is not a projectile like a flying bullet, and is never 
attracted by metal or anything else. Every part of a lightning 
flash is made at the identical spot you see it. 

FIVE 

The previous electrical conditions that cause lightning operate 
under intelligent laws and lightning protection can only be at¬ 
tained by aiding these laws to govern the previous electrical con¬ 
dition before the lightning flash develops and not by trying to catch 
the lightning flash. 

SIX 

Electro Static Sparks are ever liable to occur at the contacts 
of loosely connected metals at the instant of a near lightning dis¬ 
charge. 


NINE SCIENTIFIC MAXIMS RELATIVE TO PETROLEUM 
STORAGE TANKS. THEY WILL BE EXPLAINED AS WE 

PROCEED. CRITICIZE EACH ONE THOUGHTFULLY 
IN ADVANCE THEN STUDY THEM CAREFULLY 

IN THE TEXT 

ONE 

Petroleum Storage Tanks with properly riveted steel roofs and closed winch boxes 
are practically immune from lightning danger. 

TWO 

The Majority of Petroleum Tank Fires are caused by electro static sparks at elec¬ 
trical resisting roof contacts at the instant of a lightning discharge anywhere in the 
vicinity and sometimes at remote distances. 

THREE 

Petroleum Storage Tank Fires are never caused by inflammable vapors in the at¬ 
mosphere away from and above a tank. 

FOUR 

The sudden change in the Earth’s Electrical Field at the instant of a lightning dis¬ 
charge is the occasion for electro static sparks at all electrical resisting roof connections, 
or loose sheet metal contacts, and all such tanks situated within this electrified earth area 
are in more or less danger at that instant. 

FIVE 

Electric Light wires or any other overhead wires leading to a tank greatly endanger 
the tank from lightning discharges anywhere along the line. 

SIX 

To seal a Petroleum Storage Tank vapor tight with a non-electrical conducting ma¬ 
terial affords no lightning protection whatever, but may increase the lightning hazard. 

. SEVEN 

A direct Lightning Discharge at a tank under normal tank conditions will occur at 
the edge of the tank and preferably at the head of the stair railing. 

EIGHT 

A Lightning Discharge can only occur at one tank in any tank farm at the same 
instant, but other tanks are endangered at that instant from electric discharges from 
their own roofs. 

NINE 

The Brush Electric Discharge may cause a tank fire before a lightning flash develops. 



Fig. 1 

A Graphical Illustration of the Discharge of the Earth’s Electrical Field 


This is an unusually instructive picture. 

It tells without words why a lightning flash occurs. 

We see a flash between the cloud and the tree. 

We see how the cloud at one e id and the earth at the other end 
of the flash give up their electric charges to make the lightning. 

We see some dead cattle by a wire fence and some petroleum 
tanks on fire along a pipe line. 

We see a greater electrical in tensity on the earth’s surface 
around the tree and along the wire fence and along the pipe line 
than elsewhere. 

The story that follows will tell how and why the tanks take fire 
at the instant of the flash at the tree. 


s 














THE DISCHARGE OF THE EARTH’S ELECTRICAL FIELD 
HOW IT CAUSES PETROLEUM TANK FIRES 


Scientific knowledge can save tanks. 

A lightning flash is not an accident or a freak of nature, but an intelligent creation, 
and every petroleum tank that burns through lightning causes is a reproach to our in¬ 
telligence. 

That this is true is clearly evidenced by the fact that nearly all tank fires occur on 
special tank constructions. 7 

Insurance records prove beyond any question that wooden roofed tanks, no differ¬ 
ence how well they may be sealed up, are a far more serious lightning hazard than are 
steel roofed tanks. 

If the reason for the excess fires on wooden roofed tanks were understood by the 
petroleum producers and by the Underwriters these fires would not be permitted, so we 
may readily conclude every tank fire from lightning causes is a special assessment on 
our ignorance. % ^ 

The reasons for these tank fires, however, are quite within our reach and subject 
to our control, and our theme shall be to render these reasons intelligible and save the 
tanks. 

LIGHTNING AND ELECTRICITY NOT THE SAME THING 

The common statement that lightning and electricity are one and the same thing is 
a little confusing. If we should say fire and coal are one and the same thing, that would 
not sound very sensible, but it is exactly as sensible as to say lightning and electricity 
are one and the same thing. We can have coal without fire and we can have electricity 
without lightning, but we cannot have fire without fuel, neither can we have lightning 
without electricity. We should think of this intelligently, for in saving the tanks we 
have to settle with electricity, not with lightning. 

Lightning never springs into existence parentless of previous electrical conditions, 
and lightning protection for the tanks is only attainable by knowledge of what these pre¬ 
vious electrical conditions are doing to the tanks and not by some fool idea of attempt¬ 
ing to catch a lightning flash. 

WHAT THE PREVIOUS ELECTRICAL CONDITIONS ARE DOING TO THE TANKS 

When a cloud is acquiring a charge of electricity previous to a lightning discharge, 
it exerts an electrical influence on the earth’s surface beneath it by which this surface 
takes on an electrical charge of opposite sign. This charged earth’s surface is called 
“The Earth’s Electrical Field,” which together with the charged cloud constitute the 
“Previous Electrical Conditions” to which we have referred, and all tanks within this 
field are subject to this electrical influence. 

Before the lightning flash occurs, the electrical charge induced by the cloud is dis¬ 
tributed over the earth’s electrical field the same as on the cloud, and every acre has 
more or less of a charge on its surface which is being increased, maintained and bound 
by the growing charge on the cloud. 

A 55,000 barrel tank covers a half acre and the entire charge of that half acre is 
on the upper surface of the roof of the tank—for this roof is a part of the earth’s 
electrical field—this electrical charge on the roof is acquired gradually or during the pe¬ 
riod between one lightning discharge and the next. 

When the earth’s electrical field is suddenly discharged, causing lightning, the half 


6 


acre on top of the tank discharges suddenly at that instant, regardless of where the 
flash occurs and our problem is— How can we get this ha lf acre charge off the roof with¬ 
out setting the tank on fire? 


This great problem is associated almost entirely on tanks with wooden roofs with 
or without thin metallic sheathing, or with any container the roof of which has poor 
electrical conducting continuity. 

Before we give detailed reasons for the tank fires we offer this little Dictum: 

"If there was no electrical resistance on the tank roofs and no inflammable gases in con¬ 
tact with the outside of the roof, there would never be any tank fires from lightning causes, 
never any.” 

We may here state—lightning and electro static sparks can only occur on poor elec¬ 
trical conductors, such as air or other electrical resisting media, and never on a good 
and efficient electrical conductor, such as metal, and that electricity always seeks to dis¬ 
charge through the path of least resistance. 

If all kinds of materials conducted electricity alike there would never be any light¬ 
ning or any electro-static sparks. Of the hundreds of thousands of various known sub¬ 
stances, no two of them conduct electricity alike. Some kinds conducting thousands of 
times, some kinds conducting millions of times and some kinds conducting billions of 
times better than others.*! This difference in the electrical conductivity of various 
things is the true reason why we ever have lightning and tank fires from electrical 
causes. This knowledge and how to use it rests in the very heart of the fine problem 
of saving the tanks. 

The following nine principles, with the evidence given in each case, will be inter¬ 
esting and instructive to the petroleum industry and to the general public. These 
principles are statements of scientific facts, all of which can be demonstrated in the lab¬ 
oratory and all of which are supported by reason or by observation in the field. 

These principles will command the approval of scientific and technical men, all of 
whom will agree there is no means of lightning protection for petroleum storage tanks 
except through knowledge of tank conditions and their ability to govern static electrical 
discharges. 


*The Electrical Markings shown along the wire fences and metallic pipe lines on the earth’s 
electrical field. Fig. 1, are exactly as they appear in laboratory experiments, at the instant of 
the discharge of a semi-conducting condenser when metallic cords are lying on its surface. 

Ordinary soil is only a semi-conductor, and metallic lines, such as wire fences or pipe lines 
laid on or in the earth’s electrical field, attempt in the same way to convey all of the elec¬ 
tricity near them when the earth’s electrical field discharges at the instant of a lightning flash. 

This explains the intense electrical conditions so dangerous to animals standing near wire 
fences during lightning discharges, a condition which never exists (dong wooden fences. 

It also explains the serious electrical influence of extended metallic pipe lines, on the tanks 
with which they are related, at the instant of the discharge of the earth’s electrical field. 

•j- For electrical resistance and relative conductance of various substances, see Elementary 
Lessons in Electricity and Magnetism, page 409, by Sylvanus Thompson. 


7 






PRINCIPLE ONE 


A Petroleum Storage tank can not take fire from 
lightning causes on the inside of the tank, for neither 
lightning or electro static sparks can occur within a 
metalic structure. 



Fig. 2 

Immune from Lightning Danger Within 































Evidence to Principle One 

This principle was first demonstrated and proved by that illustrious scientist, 
Michael Faraday, more than one hundred years ago and can be verified beyond intelli¬ 
gent dispute by a competent man if he has the proper electrical apparatus. 

The reason for the principle is this “Electricity of either sign is self repellent” 
and because of this, static charges can only exist on the outer surfaces and edges of 
metallic structures. 

That means—The electrical charge on any tank previous to a lightning discharge is 
all on the outside and none whatever on the inside of the tank; therefore, lightning and 
electro static sparks due to lightning discharges must always be on the outside of any 
metallic petroleum tank as well as the outside of any other metallic structure. 

The fact that no one was ever injured or shocked from lightning causes within a 
railway train or within a steel structural building is practical evidence in support of 
the principle. 

The twenty to fifty story skyscrapers of our large cities are immune from lightning 
influence within because they are steel structural in their framework, and induced elec¬ 
trical charges—being self repellent—can only exist on the outside of any metallic frame¬ 
work and especially on the upper surface and edges, for these are nearest the cloud. 

A wooden flag pole or any poor electrical conducting material or a man standing 
on top of such building might be in imminent danger during a lightning discharge, but 
all within would be absolutely safe. 

Railway coaches and engines are steel cages and for that reason a static electric 
charge cannot exist within. It might be dangerous on the top of a train during a thun¬ 
der storm, but not the slightest danger of the mildest electrical shock to those within. 

The same is true of a steel petroleum storage tank, all the dangers are on the out¬ 
side and none whatever within till the fire starts on the outside. 

Knowledge of this principle is valuable and should prompt us to intelligent inquiry 
into the true reason for tank fires during thunder storms, for we can never correct these 
reasons till we know what they are. 


9 


PRINCIPLE TWO 

Petroleum tank fires from lightning causes can only 
start in inflammable gases on the outside and in close 
relation to the tank roof, and never from inflammable 
gases high above a tank, which ignite and back fire to 
one or more tanks. 



- ni fo fr ■ r ^ ^ 


Fig. 3 

Why Does the Torch Not Light the Gas? 


10 





Evidence to Principle Two 

Experiments of Sir Boverton Redwood, Dr. Du Pre and others, as well as the author, 
prove that one percent or less of petroleum gas mixed with air is not inflammable. 

Avogadro’s Law of Gas Diffusion is an accepted maxim of physics and proves that 
any escaping gas in free air distributes itself uniformly in space. 

That means—the ratio of mixture of any gas with free air will decrease in propor¬ 
tion to the cube of its distance from the place of escape, which means—a one percent 
petroleum gas mixture would be a physical impossibility in free air at any material dis¬ 
tance from a tank under any natural conditions of evaporation. Reference to the Ard¬ 
more disaster will be found in another part of this book. 

The lighter gases in petroleum evaporate most readily, and though these gases are 
heavier than air their diffusion after their escape is practically the same in all directions 
if there is no wind. If the wind was blowing at the rate of ten miles an hour—which 
is less than the average velocity in Oklahoma—diffusion would be so rapid in that direc¬ 
tion that an inflammable air gas from a storage tank could only exist within a few inches 
of the place of its escape. 

The illustration, Fig. 3, shows a man holding a flaming torch near a gas flowing pipe 
in the field, the torch being held where the gas mixture is too thin to ignite because of 
rapid diffusion. Of course, the pressure and volume of gas flowing from the pipe would 
determine the inflammable distance where the air is not confined as in a house. 

If you have a gas jet in your home try the experiment. Open the jet so the gas 
will flow freely and see how near you can come to it with a burning match before it will 
ignite. The experiment will convey an intelligent practical lesson; that is what you 
want. 



1 1 











PRINCIPLE THREE 

A steel roofed tank if gas tight in its roof connections, 
with intelligent means for its pressure gasses to escape 
elsewhere than thru the tank roof, could never burn 
thru lightning causes. 



Fig. 4 


Close that Winch Box 


12 












































Evidence to Principle Three 

The fact that lightning losses rarely occur with good steel roofed tanks is not due to 
chance but to good and sufficient reasons. These reasons can be conclusively demon¬ 
strated in the laboratory, and justify the assertion that lightning could never cause dam¬ 
age to a steel roofed tank, if it had intelligent care. 

Lightning and electro static sparks can only occur in an electric resisting medium 
such as air, but never on a good electric conductor such as a steel tank, where all the 
separate metal plates are well connected in continuous electrical contact. 

A lightning flash might take place between the cloud and the edge of the tank, but 
no lightning could occur between the edge of the tank and the ground, as electricity 
makes no lightning where it has no resistance, and there is less resistance in the im¬ 
mense body of a steel tank than almost anything we can name. 

We have an illustration in the case of the electric light in our homes. The light is 
on an electric resisting filament in a glass globe, but there is neither light nor fire on the 
conducting wire that leads the electricity to the filament. In like manner lightning can 
only occur in air or electrical resisting substances. 

If a steel roofed tank is gas tight on its roof, lightning can not start a fire there, 
for the flash is all outside of the tank. (See evidence to Principle One.) 

The illustration, Fig. 4, shows a lightning flash at the head of the stair railing of a 
steel roofed tank. It also shows an open winch box near the stairway through which 
gas is escaping. A condition like this is too much for any tank, especially a steel roofed 
tank, as all of the evaporation would come through this opening. Other provision should 
be made for the gas escape. 

When the causes for lightning tank fires are more intelligently considered, and 
tanks properly conditioned and equipped, there will be few tank fires from lightning 
causes. 


13 


PRINCIPLE FOUR 

Tanks with wooden roofs, whether covered with 
gravel, asphaltum paper, loosely connected sheets of 
metal or anything else with poor electrical continuity, 
may take fire at the instant of a lightning discharge even 
tho the lightning flash is not near the tanks. 



Fig. 5 

A Spark at the Trolley Wheel. Why? 






























Evidence to Principle Four 

This principle has a tremendous meaning to the nation as well as to the petroleum 
interests, as it involves the most serious lightning problem on earth. 

The best evidences in support of the principle are the experiences of the petroleum 
producers and the records of the oil insurance companies. 

The principle is laid in a fundamental law of science, which treats of the nature of 
lightning discharges. This law will be easily comprehended by referring to Fig. 1 and 
the description of the discharge of the earth’s electrical field on pages 5, 6 and 7 of this 
book. 

In this you will learn that lightning is the result of the sudden discharge of elec¬ 
trical conditions that existed on the cloud and on the earth’s surface previous to the ap¬ 
pearance of the lightning flash. You will also learn that one-half acre of this earth’s 
electrical field is on the top of every 55,000 barrel tank beneath the cloud. 

You will further learn that the electrical charge that was bound on each tank roof 
by the inductive influence of the charging cloud was suddenly released at the instant of 
the lightning flash and as suddenly returned to earth and that the danger to the tanks 
from this cause depends entirely on how this previously bound charge got off the roof, 
and that is the secret we want to explain. 

The separate plates of a L Y are so well riveted together and to the tank rim 

that any electrical charge on u ^of can come off without the slightest interference or 
resistance. That is the whole secret of the safety of the steel roof, but the thin sheets 
of metal on a wooden roof are not electrically connected that way. They are attached 
with nails to the wooden roof and these sheets are soon loosened, due to their co-effi¬ 
cient of expansion in varying temperatures. The roof also has very inferior connection 
to the tank rim compared with that of a steel roof. 

The greatest danger to this class of tanks lies in these loose metallic connections on 
the roof, for an electrical charge coming off such a roof meets with more or less resist¬ 
ance at these imperfect metallic contacts, and electro static sparks result at the cross¬ 
ings because of this resistance and one or half a dozen tanks may take fire at the same 
instant dependent entirely on the inflammability of the escaping gas where the spark 
occurs. 

The writer finds through experimental tests that wooden roof tanks without sheet 
metal take fire only at the edges, but those with sheet metal may take fire anywhere on 
the roof where gas is escaping. He also finds sparks very frequently occur without 
causing a fire, but the greater the evaporation the more readily the sparks will start 
the conflagration. 

The illustration here given, Fig. 5, of the electric street car shows a phenomenon 
with which we are all familiar. It is designed to show what happens between loosely 
connected metals charged with electricity. 

The trolley wheel has bumped from its contact with the charged wire and we ob¬ 
serve a spark instantly takes place at the break. If this happened in an inflammable gas 
a fire would result. 


15 


Well, that is exactly what does happen among the tanks at the instant of the dis¬ 
charge of the Earth’s Electrical Field unless provision is made to prevent it, for every 
sheet of metal on the tank roof had a static charge on its upper surface, and when this 
is suddenly released by a lightning flash anywhere near or far, it means “Danger from 
electro static sparks in loose metallic connections on the tank roof” the same as you wit¬ 
ness at the trolley wheel in the picture. 

PRACTICAL EVIDENCE 

V 


The following extraordinary record is given to confirm the scientific explanation we 
have tried to make clear. 

At the five critical tank stations, viz., Avondale, Elvista, Sour Lake, Lufkin and Par- 
ryman, forty-six tanks were burned during the seasons 1912, 1913, 1914, 1915, 1916 and 
till June 1917. That was an average of seven tanks a year. In none of these years were 
less than three tanks burned and in some years as many as twelve. 

Since 1917 the West Dodd System of Spark Prevention has been on the tanks at these 
stations and though three years have passed since these equipments were put on there 
has never since been a tank loss at either of these stations. 

'V 

.2353 

By the rule of expectancy based on the record there should have been ten to twenty 
more tanks burned at these stations since June, 1917, if the equipments had not saved 
them. ? 

This practical test is sufficient to prove to a reasonable mind that the fires at these 
stations had been due to electro static sparks in inflammable vapors between disconnected 
metals on the tank roofs as the spark preventing system alone is all that is used on any 
of the tanks at either of these stations, and nothing whatever to guard against a direct 
lightning flash at a tank. 

It is clearly evident a direct lightning flash in contact with a gas leaky roof would 
start a fire at any of these tanks in defiance of the spark preventing system, but the 
fact that this did not happen in the last three years is reasonable evidence that electro 
static sparks had previously done the business. 

It is only fair to here state, Elvista has been practically abandoned, but generous 
allowance has been made in the estimated number of tanks saved by the equipments. 


je 


16 


PRINCIPLE FIVE 

A direct lightning discharge at a tank is a frequent 
occurrence and under ordinary tank construction will 
take place at the edge of the roof and not in the center 
unless some metallic projection is there. 



Fig. 6 

The steel roofed tanks A and C can withstand it. The wooden roofed tanks B and D are 

in danger from electro static sparks 


































Evidence to Principle Five 

From a scientific consideration a tank is a very natural point for the discharge of the 
earth’s electrical field provided cloud and atmospheric conditions were uniform, but the 
distance between the tank and the cloud is relatively large compared with the distance 
between the top of the tank and the ground, and cloud formation and atmospheric con¬ 
ditions are ever varying which would almost equalize the chances for the path of least 
electric resistance between the cloud and objects of equal height unless they were near 
to each other in which event it would discharge through the best conductor. 

To that extent it would choose the tank and discharge at the tank rim and prefer¬ 
ably at the head of the iron stair railing. 

It is a matter of general observation that lightning at houses or barns occurs at the 
corners or edges if they have no chimneys or cupolas. If they have ordinary chimneys 
or cupolas near the center of the roof and not near the ends lightning would still attack 
the corners or ends of the roof unless there should be tin valleys or other metallic ways 
on the roof leading to such chimneys or cupolas. 

The reason for this is “The induced electricity of either sign is self-repellent” which 
makes the previous electrical conditions more intense at the extremities. 

Laboratory experiments show, a lightning discharge at a tank would occur at the 
edges even if the center of the roof were three times as high as ordinarily constructed 
unless there was a metallic projection on the roof. 

A metallic pipe four feet high on the roof center would cause the discharge to take 
place there but if a smooth metallic -arched roof, extended twenty feet above said pipe, 
the discharge would occur at the tank edge or lower edge of the roof. 

In illustration Fig. 6 A and C represent well riveted steel roofed tanks. The light¬ 
ning flash can not harm them for there are no inflammable gases without on the roof 
and lightning can not get within. 

The lightning flash at “C” endangers the wooden roofed tanks “B” and “D” through 
sparking possibilities at their loosely connected metallic contacts while “A” is spark 
proof. 


“B” and “D” would have no chance of escape whatever if the flash occurred at the 
edge of their leaky roofs, as the whole lightning discharge is immensely more dangerous 
than any single roof discharge. 


1 


PRINCIPLE SIX 


Electric light or other wires extending to a tank are 
a source of imminent danger to the tank during thunder 
storms especially to tanks with poor electrical continuity 
on their roofs. 



Fig. 7 

A foolish arrangement 


19 
































Evidence to Principle Six 

It would hardly seem necessary to offer any evidence in support of principle six. 

Even if one had little scientific knowledge his observation should furnish sufficient 
evidence to satisfy the validity of the principle. 

Years ago before the telegraph companies put ground wires on their line poles, a 
lightning discharge would sometimes split half a dozen or more poles in a row. 

These lessons taught the telegraph companies to put ground wires on every fifth 
pole which seems to be sufficient to protect their line poles and nothing worse now hap¬ 
pens during a lightning discharge on their lines than a few minor sparks in the telegraph 
office. ! 

This method, however, would not be dependable where a petroleum storage tank is 
on the line as the tank because of its splendid electrical connection through its pipe lines 
to the earth’s electrical field would take on a super charge because of the charged over¬ 
head wire, even if all the poles along the line were metal. This is easily demonstrated in 
the laboratory by putting an electriscope on top of the experimental tank which demon¬ 
strates the previous electrical condition before the discharge takes place and the in¬ 
creased electro static sparking that results at the instant of the discharge. 

Furthermore, the line pole on top of the tank is by far the shortest pole and it is 
placed near the winch box as it carries the reflector—Fig. 7—that throws the light into 
the tank. If the winch box should be open, as is frequently the case, what could you ex¬ 
pect but a fire at that tank if a lightning flash occurred on the line a mile away. 

The day is not far distant when the loss of the nation’s Petroleum through light¬ 
ning causes will be considered criminal. 



20 











PRINCIPLE SEVEN 


Only one lightning flash can occur within the limits 
of any tank farm at the same instant. Such thing as 
lightning forking in the air and occurring at two or 
more tanks during the same lightning discharge is im¬ 
possible. 



Fig. 8 

Fortv-two cattle owned by Mr. G. H. Kiefer killed by one lightning discharge on his farm 
in Kit Carson County, Colorado. Insurance paid by the Home Insurance 

Company of New York 


21 








Evidence to Principle Seven 

It is difficult to give proof of this principle from observation because lightning, if 
near, is blinding and no one can see the flash because of its intense and sudden bright¬ 
ness. A chain of lightning can be seen at a distance, but no branching in its vicinity 
occurs near the ground. If multiple flashes occur they are well separated. 

When more than one tank takes fire at the instant of a lightning discharge one of 
them might or might not contact with the flash, but all the other tank fires would result 
from electro static sparks due to the discharge of the bound charges on their roofs. 

The evidence in support of this principle is purely scientific. 

All gases in their normal condition, including air, are the poorest of all conductors. 
When a lightning discharge opens a path through the resisting air that path for a second 
or two becomes a good conductor between the cloud and earth and many electrical pulsa¬ 
tions occur through that channel during a discharge for the molecules of air along that 
crooked path have exploded because of an electrical strain, making them ions or electric 
carriers which make this ionized path a conductor between cloud and earth till the cloud 
has fully discharged. 

It takes tremendous electric pressure to open this path. To this end the cloud unites 
its electrical power through various branches, though not always visible, while the earth’s 
electrical field being a better conductor than the cloud can focus its forces at the re¬ 
quired spot without branches in the air. 

The reason then for one main lightning flash at the earth is because one channel 
through the air is easier to break down than two especially where connected metallic 
lines extend through the soil. 

The illustration—Fig. 8—is interesting. It shows forty-two cattle killed for Mr. 
Kieffer by one lightning discharge and not by forty-two separate lightning flashes. 

The same kind of discharge that killed these cattle could burn forty-two tanks if the 
conditions were right. 


22 


PRINCIPLE EIGHT 

A large concrete reservoir is a risky petroleum con¬ 
tainer during a local thunder storm unless all of the 
reinforcing metallic fabric within the concrete is skill¬ 
fully connected before the concrete is put on. 



Fig. 9 

The 350,000 barrel reservoir “B” at Gainesville, Texas 
A concrete Lesson with a Moral 


23 













Evidence to Principle Eight 

Mystery vanishes in the light of knowledge and here we offer a wee object lesson 
Fig. 9. 

The concrete reservoir should never burn from lightning causes if its metallic rein¬ 
forcing material is properly connected during its construction, and this is no job for 
an indifferent workman or a charlatan. 

The danger from electro static sparks is even greater than that of the wooden roofed 
tank unless its metallic parts are intelligently connected. 

If the reservoir—roof and all—are two or three feet under moist ground it is safer, 
for it is in a measure encaged in electrical conducting earth, but even then its reinforc¬ 
ing metals should be well connected everywhere, lest the surface earth dry out and light¬ 
ning begins before the rain but no conditions justify loosely connecting metallic fabric in 
a petroleum reservoir. 

If all substances conducted electricity alike there could never be any lightning dis¬ 
charges and no tanks would ever burn from that cause, but substances are not made 
that way and therein lies the danger. 

The reader should see page 409 of Elementary Lessons in Electricity and Magnetism 
by Sylvanus Thompson, to learn something of this difference in electrical conductivity in 
certain materials. 

There are probably 300,000 different kinds of materials known and no two conduct 
electricity alike and even the same one will vary under different conditions but under 
any conditions metal is millions of times better conductor than earth and better still when 
compared with concrete. 

The reader should try to absorb the full meaning of the discharge of the earth’s 
electrical field illustrated in Fig. 1 and described on pages 5, 6 and 7 and learn “The top 
of every tank or reservoir under a charged cloud is a part of the earth’s electrical 
field.” 


Ordinary soil is not a very good conductor but the metal pipes in the soil which 
are attached to a reservoir or tank are conductors of the first order and at the instant 
of a lightning discharge the tanks and reservoirs are more suddenly and generously 
relieved of their part of the earth’s electrical field because of these extended pipe lines, 
all of which is easily demonstrated in miniature in the laboratory. (See Fig. 1 and foot 
note on page 7). 

In this connection Fig. 9 is interesting. This 350,000 barrel reservoir at Gainesville, 
Texas, was burned through lightning causes April 16, 1918. It was constructed on the 
lowest ground in the neighborhood and practically all of it except the roof was beneath 
the surface level. 

There were eight 55,000 barrel steel tanks on the higher ground surrounding it, and 
a 75 foot metallic flag pole on high ground within 800 ft. of it. None of the surrounding 
tanks were in any way affected, probably because they had been previously equipped to 
prevent sparking. 

The flash may have occurred at the 75 foot flag pole on the hill but hardly possible 
at the underground reservoir in the hollow with so many tall metallic structures surround¬ 
ing it in on higher ground. Experimental research and reason say “It never did.” 


24 


This reservoir had a roof surface of 2% acres. That means 2% acres of the earth’s 
electrical field was on reservoir “B” before the flash occurred. Within this concrete roof 
was 2 % acres of loosely connected metal fabric, this roof fabric was separated from the 
fabric in the body of the reservoir as much as six or more inches, where the roof rests 
on the wall. 

When the lightning discharge occurred the 2% acres of the earth’s electrical field on 
top of the reservoir discharged at that moment and the metal fabric delivered the goods 
as far as the resistance gap at the lower edge of the roof. Then came a six-inch flash 
and an explosion, and Fig. 9 shows the sequel. 

It is probable there were many tiny sparks within the concrete any of which could 
start a fire if in contact with inflammable vapor, but all of which may have been innocent 
because of their concealment, but in any event there should be a law against these sparks 
on top of a petroleum tank or reservoir. 

Some years ago it is said a 2,000,000 barrel reservoir was burned during a thunder 
storm at Humble, Okla., and it is said “Other underground reservoirs in Oklahoma were 
burned in 1917.” If this is correct, the evidence will show that concrete reservoirs con¬ 
structed as described are the most serious of all lightning hazards for petroleum storage. 

The writer, however, is quite convinced that the concrete system of storage can be 
a very safe system and is hopeful this lesson will result in much good to the petroleum 
interests. 

The time is coming and not far distant when “Uncle Sam” will not permit these 
lightning losses for they have a national as well as an individual meaning. 



25 









PRINCIPLE NINE 

A very tall metallic tower standing within or near a 
petroleum tank farm would endanger every tank in the 
farm during a local thunder storm unless their roofs 
are spark-proof and the taller the tower the greater the 
danger. 



Fig. 10 

THE UNLUCKY 13 

This instructive and interesting object lesson was photographed July 30, 1918, on the 

premises of Mr. D. L. Haffner, in Pickway Co., Ohio 


26 







Evidence to Principle Nine 

Perhaps the most convincing proof of this principle is the fact that it has been tried 
by some of the largest petroleum producers and the principle found to be true by the 
disastrous consequences to the tanks. 

The idea was “The tower would keep lightning away from the tanks” and the idea 
was perfectly correct. If the tower is tall enough a lightning flash could never get near 
any of these tanks but nothing else could cause more tank fires from electric influences 
than such a tower. 

A tower so tall would be the earth terminal for all lightning discharges within forty 
rods. That means, “The earth’s electrical field would concentrate among the tanks and 
discharge at the top of the tower. 

No lightning would be nearer the tanks than the top of the tower and no inflamma¬ 
ble gas would be nearer the top of the tower than the distance to the tanks but there 
would be a pyrotechnic display on the top of all tanks the roofs of which had poor elec¬ 
trical continuity and their chances of taking fire would depend entirely on the gas mix¬ 
ture among the sparks. 

This thought never occurred to those who tried the expensive experiment. They 
reasoned “Lightning fell down out of a cloud and struck the tanks and the tower would 
catch it on the way down.” Better knowledge would have taught them to attend to the 
electrical condition of their tanks first and erect the tower afterwards. 

The author is inclined to believe these towers or masts did not get a square deal. They 
at least would insure against a direct lightning discharge at a tank, and while such 
towers might greatly intensify sparking possibilities on poorly connected tank roofs these 
miniature induced charges on the tank roof are very much easier to control than would 
be the whole earth’s electrical field through a lightning discharge at a tank. Experi¬ 
mental failure, however, should help to clear the way for the truth, for victory is at¬ 
tainable through knowledge of the facts. 

The illustration Fig. 10 shows what happened to the “Unlucky 13.” It is hardly a 
parallel case to our principle, but it is evident “that tree tower was a bad thing in the 
center of that group” and it carries a suggestion that a tall tower among the tanks would 
have a similar meaning unless their roofs were spark proof. 


27 


Fig. 11 



The West Dodd Tank Protector 

Illustrating the equipment of a 55,000 barrel tank 

8 Concentric Copper Cables on the Roof. 

64 Radial Copper Cables connected electrically every six feet to the tank rim, also 
at every crossing of every concentric copper cable, also to the large brass cap at the peak 
of the roof. 

1,000 or more electrical connections of the copper cables to the various loosely con¬ 
nected metallic sheets and pipes on the roof to neutralize sparking possibilities between 
the sheets. 

128 Cap Screw connections on all sheet metal roofs where sheets are not riveted or 
poorly riveted to the tank rim. 

A sharp copper point in the brass plate at the peak of the roof to prevent a dis¬ 
charge at the tank rim and silently reduce the electrical intensity at the tank previous to 
a lightning discharge. 

It is relatively inexpensive. 

It will not deteriorate. 

It costs nothing to maintain. 


28 


















































































































































































































































TO THE PETROLEUM INDUSTRY AND THOSE INTERESTED 

In the foregoing nine principles we have told you what we know to be true relative 
to tank fires from lightning causes which we hope you have found interesting and in¬ 
structive and you have. 

To prevent a tank fire is much better than to permit the fire and extinguish it after 
it has done thousands of dollars of damage and our theme now is to tell how these light¬ 
ning losses may be prevented. 

The first essential to intelligent means for tank protection is knowledge of why they 
take fire. The statements in the nine principles given are dictums of science which 
briefly convey this knowledge. The evidence which follows each principle is an effort 
to prove the principle is sound. ' 

From these principles we learn that electro static sparks during lightning discharges 
are the most prolific source of tank fires and that these sparks occur between unskill- 
fully connected metallic parts on a wooden roof or at the contact of a wooden roof with 
the tank rim. 

With this knowledge we can approach the problem of tank protection intelligently, 
without this knowledge any attempt at protection is puerile and futile and the tanks will 
continue to burn. 

Based on this knowledge we herewith exemplify a system developed by the author by 
which tanks with roofs having poor or discontinuous electrical conductivity may be 
saved from fires due to lightning discharges. 

THE WEST DODD LIGHTNING PROTECTION SYSTEM 
FOR PETROLEUM STORAGE TANKS 

The illustration Fig. 11 is designed to show a net work of copper cables electrically 
connecting every sheet of metal on the roof of a 55,000 barrel tank to every other sheet 
and to the system, also electrically connecting the roof and every part of it to the tank 
rim in sixty-four separate places about six feet apart. 

The sixty-four radial conducting copper cables which connect the roof electrically 
to the tank are also electrically connected to the concentric girdling copper cables on 
the tank roof, also to the brass plate in which the point is electrically attached. The 
object being to have every piece of metal on the roof so well connected that electro static 
sparks can not occur any more than on a well connected steel roof. 

“A,” Fig. 11, represents a section of sheet metal on a wooden roof, showing how 
each metal sheet on the roof comes into metallic union with the system. 

So many connections to the tank rim would not be necessary if the various sheets of 
metal on the roof were not subject to such variations of contact due to their co-efficient 
of expansion in changing temperatures. 

The evidence given to principle four indicates these sixty-four connections have 
been sufficient to prevent electro static sparks under any normal electrical tank condi¬ 
tions. 

THE FUNCTION OF THE POINT 

Without the point a lightning discharge could occur at the tank rim among the 
inflammable gases—Principle Five. With the point the flash could not occur at the tank 
rim but at the point fifty feet away from the tank rim. 


29 


This is not because the point attracts the lightning. The belief that anything at¬ 
tracts lightning is an absurdity. 

Lightning results from previous electrical conditions and these electrical conditions 
are more intense at an upright point than anywhere else, because a point has little sur¬ 
face. 


If your eyes were big enough so you could see the air, the function of a point would 
appear simple enough. The air is made up of minute grains, called molecules, well sep¬ 
arated from each other and in eternal motion, but you can not see them. 

Before the earth’s electrical field and the cloud are ready to discharge through a 
lightning flash the molecules of air in countless trillions are attracted to the super¬ 
charged point and each takes on an electrical charge from the point and flies away with 
it. This rush of air molecules from a charged point is called the “Electrical Wind” and 
in laboratory experiments is strong enough to extinguish a burning match or spin a 
pointed wheel. It is also luminous in the dark, reference to which appears under the title, 
“Saint Elmo’s Fire.” 

These charged molecules are also called ions, and ionized air is a better electrical 
conductor than any other air, and that is why the flash occurs at the point, from which 
we may observe. Nature works intelligently and asks for intelligent consideration. 

If these ions could fly away with the charge rapidly enough it would prevent the 
flash at the tank entirely, but in any event they reduce its intensity as well as dictate 
the place for the lightning flash if it has to be at the tank. 

The system can be used either with or without the point. Without the point it is 
only a spai k preventer, with the point it is a spark preventer and also deals with the 
greater problem of the direct discharge. 



30 































WOULD THIS SYSTEM GIVE ABSOLUTE LIGHTNING PROTECTION UNDER ANY 

AND EVERY POSSIBLE CONDITION? 


That is a fearful question to apply to a petroleum storage tank, but we may as well 
face the issue squarely and say “Absolute” is probably too strong a word to use with the 
terms “Any and every possible condition.” 

We confess it is easier to save a tank from the discharge from its own roof surface 
than if the discharge from the whole earth’s electrical field passed through it, as would 
be the case if the flash was at the tank. 

The great majority of tank fires seem to be due to electro static sparks on their roofs 
at the instant of a lightning discharge elsewhere, as evidenced in principles four and nine 
and protection to this class can reasonably be brought under the term “Absolute” but *ve 
could not speak without qualifying terms on the minority class. 

Points were not used on the tanks specified in the evidence to principle four and else¬ 
where. These were left off after some discussion with those interested to learn to what 
extent electro static sparks had caused the previous enormous losses at these stations, 
with full knowledge a direct lightning discharge through any of these tanks would in all 
probability start a fire in defiance of the spark preventer, and the fact that not a light¬ 
ning loss has occurred at either of these stations since they were equipped is reasonable 
assurance the majority of all tank fires are preventable, absolutely. 

A direct lightning discharge through a tank the roof of which has loose metallic sheets 
in near but imperfect contact, is a different proposition, for when the electricity from every 
other tank roof as well as the surrounding country has to meet the cloud conditions through 
a single tank, there is danger of an overflow causing sparks at some of the near but loose 
connections of the sheet metal and we frankly admit that is where “Absolute” may not 
appear with integrity, even though no tank has yet been lost where points have been 
applied. It is here, however, the benefits of a properly erected point have great value 
in either preventing a lightning discharge at the tank or reducing its intensity so the 
sixty-four copper cables attached to the tank rim every six feet and electrically attached 
to every sheet of metal on the tank roof may be able in the majority of this minority 
class to save the tanks. 

It has occurred to the writer that the tower mentioned in principle nine is not a fool 
idea if the job is intelligently finished for while it might cause additional discharges 
in that vicinity, it would not be difficult to make the surrounding tanks safe. The six-foot 
point on the peak of the tank, however, would in no way cause additional discharges, but 
would minimize them and would prevent them from occurring at the tank rim. A pointed 
tower or mast would also minimize the lightning intensity, but not prevent sparking on 
poorly arranged roofs. 

Thus far we have given a scientific exposition of how and why lightning causes tank 
fires and with knowledge of these causes have worked out a means for their protection 
and for which we offer the following guarantee. 


31 


Guarantee 

If any tank equipped with the West Dodd System of Lightning Pro¬ 
tection, with or without the point, should burn or be otherwise damaged 
by lightning within five years from date of its equipment the price 
paid to them for such equipment shall be promptly refunded. 


As evidence of good faith in this guarantee we offer the following: 

PEOPLE'S SAVINGS BANK 

CAPITAL, SURPLUS AND PROFITS $340,000.00 

THIS INFORMATION IS GIVEN IN CONFIDENCE 
AND WITHOUT PREJUDICE OR RESPONSIBILITY 
TO THIS BANK OR TO THE WRITER 

Des Moines, Iowa, February 17, 1920. 

TO WHOM IT MAY CONCERN: 

We are pleased to introduce to you the West Dodd Tank Protector Company who are 
valued clients of this bank and whom we believe are thoroughly reliable and responsible 
for any obligations they may make. 

_ Each member of this Company is well and favorably known to us, their record being 
one of great success and achievements. 

The scientific achievements of Professor West Dodd, who is the head of this Com¬ 
pany, are favorably known throughout the nation and we feel it is no exaggeration to say 
that if petroleum tanks can be protected and saved from loss by lightning, this Company 
is equipped to perform this good work. 

Any courtesies extended to this Company will be greatly appreciated. 

Yours very truly, 

« C. H. MARTIN, 

President. 


IOWA NATIONAL BANK 

CAPITAL, SURPLUS AND PROFITS 
$ 2 , 000 , 000.00 

Des Moines, Iowa, February 21, 1920. 

TO WHOM IT MAY CONCERN: 

We have been personally acquainted with Prof. West Dodd, the inventor of the West 
Dodd Tank Protector, for a great many years. We know him to be a very high-grade, 
scientific man in his line. 

We are also acquainted with all the other members of his firm. Their phenomenal 
success and financial responsibility are established on a foundation of strict integrity and 
scientific merit. ’ 

The researches of Prof. West Dodd along all lines of lightning protection, are of rec¬ 
ognized scientific value, and we believe no one in the country better qualified to save the 
nation’s petroleums from destruction by lightning than the West Dodd’Tank Protector Co. 
We commend them highly to every one. 

Very truly yours, 

GEO. A. PEARSALL, 

GEP S Vice President. 


32 



SAINT ELMOS FIRE 



Fig. 12 

The Brush Discharge 


A possible and unsuspected source of some tank fires is the Brush Electrical Dis¬ 
charge also known as St. Elmo’s Fire. 

This usually occurs in a humid atmosphere during rapid cloud formation and is a 
continuous discharge of electricity from the region where it appears. It is quite observ¬ 
able in the dark and has the appearance of a bluish pink flame from one to six inches 
long, and many continue for some minutes with a sort of hissing sound. 

On tanks it is most likely to appear at the top of the stair railing or other outer 
prominences or edges, but not at the center of the roof unless there are metallic promi¬ 
nences there. 

This phenomenon is more common on the ocean than on the land because the elec¬ 
trical resistance of sea water is much less than that of ordinary soils. The earth’s elec¬ 
trical field on the ocean can thus localize or focus its electricity more readily at any spot 


33 























































































to accommodate the cloud and stream off in a brush of ions from the crest of a wave 
or the rigging of a vessel. 

A well authenticated instance of the brush discharge occurred on Empire Tank No. 7 
at Gainesville, Texas, about 2 o’clock on the morning of April 12, 1918. Mr. Necessary, 
the gauger, was on the tank at that hour when he heard a sound which he described as 
“The crushing of dry straw” and looking around saw two flames on top of the stair rail¬ 
ing. The flames struck him with terror as he expected the tank to instantly explode and 
he rushed off between the two electric flames and down the stairs and kept going till he 
was safely outside the fire wall. 

The author has performed many laboratory experiments with the brush discharge 
and does not find it as hot as it looks. In these experiments it failed to ignite inflamma¬ 
ble gas at the points where the brush was discharging but the experimental wooden roofed 
tanks used readily took fire elsewhere while the brush was discharging. 

The brush discharge from a field tank, however, is voluminous in comparison with any 
laboratory tests, and the conclusion is irresistable that it is not a desirable thing on a 
petroleum storage tank with poor electrical roof connections. 

This discharge is illustrated at the top of the stair railing, Fig. 12, in the vicinity of 
an inflammable air gas at an open winch box. The writer is not classifying this with the 
foregoing principles as he is not prepared to say it is as dangerous as it looks, but will 
confess he would not care to be on top of a tank during the performance. 

Empire tank No. 7 had previously been equipped to prevent electro static sparking on 
the roof, otherwise the tank might have been destroyed and Mrs. Necessary a widow. 



34 







THE RUINS AT ELVISTA 


This exceedingly interesting picture, Fig. 13, has a lesson with a tremendous mean¬ 
ing. 

Twenty-three out of twenty-five large wooden roofed tanks have been here burned by 

lightning. . 

Nearly all wooden roofed tanks in adjoining territory have gone the same way. 

The writer believes the reason for the excess loss to wooden roofed tanks in this 
region is due to the salty conditions of the Elvista soil. 

Salty and alkali soils have much less electrical resistance than ordinary soils and for 
that reason the earth’s electrical field responds more readily to a lightning discharge, 
thus causing a more intense and sudden change in the electrical potential on a tank roof. 


35 





































































Pure distilled water has millions of ohms of electrical resistance and is rated as an 
insulator, while ocean water has only about 30 ohms of electrical resistance and is a fair 
conductor. Soil mixed with fresh water is only a partial conductor, but mixed with salt 
water is a good conductor. 

The writer has tested the electrical resistance of the soils at Elvista, Sour Lake, Luf¬ 
kin, Parryman, Healdton, Cushing, Tulsa, and Ponca City, and while these tests were not 
very satisfactory they did show that the greatest tank losses were on soils with the least 
electrical resistance. 

Experiments in the laboratory clearly demonstrate that tanks with interruptions in 
their roof electrical conductivity give far more intense electro static sparks if they are on 
a good electrical conducting field. 

If there was no electrical resistance on the tank roofs they would do no sparking, so 
it would seem steel roofed tanks or roofs without electrical resistance could withstand El¬ 
vista or similar soils. 

It is fair to state that experimental tests by the author indicate heavy fuel oils do 
not readily take fire in a tank from these sparks unless the contents are much agitated as 
might be the case when a tank is being filled, but there is no reason why they should be 
given any such opportunity. 



What burning petroleum from a boiling over tank did to railway at Elvista 


36 






















The bird has a happy home in the end of the breathing pipe 



CONDITIONS OF THE SEALED TANKS 

The roof of a petroleum storage tank should not be sealed gas tight unless ample pro¬ 
vision is made for the free passage of gas out and in. 

If a gas tight empty tank was filled with any liquid of any kind from a pipe enter¬ 
ing the tank, the compressed air or other gas within would break through somewhere 
before the tank was full. If the same tank was full of any liquid and then all pumped out, 
without any air getting into the tank, the external air would crush in the walls of the 
tank before it was empty. To a thinking mind this assertion needs no proof but it in¬ 
dicates the necessity of some intelligent means of letting gas out or in the tank as it is 
being filled or emptied. 

The author has inspected many tanks in which a breathing pipe was used through 
which the gas pressure within the tank was presumed to be equalized, but in nearly all 
cases found it inefficient and gas under pressure steaming from the sealed roofs. 

The failure in these numerous cases seemed to be associated with two causes; one 
the breathing pipes were too small; two, the gauze in the end of the pipes at the fire 
wall was too small and more or less clogged up. 

Birds had their nests in the ends of some of these pipes and spiders their webs 
across the ends of some, and the sealed tank roofs leaking gas under the strain within. 

Tanks in this condition are much more dangerous during lightning discharges than if 
not sealed, for the air gas mixture within is richer in hydro carbon molecules than if the 
tank had never been sealed and more liable to take fire from electro static sparks.— 
This is demonstrable in the laboratory. 

The writer believes the breathing pipes should be larger and terminate near the 
ground well within the enclosing earth wall and should have a wide opening with gauze 
encased, all of which could be encaged for its protection. In this way the sealed roof 
would be of some value, otherwise, it adds to the danger of the tank. 

Of twenty-one large tanks burned in Texas, Oklahoma and Kansas in 1917, seven¬ 
teen of them are reported to have been sealed with a non-electrical conducting asphaltum 
material. The gases within these tanks that otherwise would have been less inflamma¬ 
ble were conserved by a process of sealing to a dangerous inflammable mixture without 
proper means of escape and left to the test of electrical discharges with results as stated. 


37 
















Kerosene evaporates very slowly under any weather conditions (see table on page 39) 
and the best way to endanger a kerosene tank is to seal it with imperfect means of gas 
escape elsewhere and then agitate the kerosene such as in filling, then the kerosene tank 
is as dangerous as any. 

These observations are no reflection on sealing tanks, but are a reflection and a con¬ 
demnation of sealing a tank with no sensible plans of letting the gas out or in as may 
be required. 

Kerosene gases are very heavy and do not diffuse as rapidly as gasoline. You can 
pour them from one dish into another like water if in a closed room and they will remain 
inflammable after several pourings. 

Kerosene is more dangerous in ocean transportation than in storage tanks surrounded 
by free air. If these vapors escape in the hold of a vessel where there is little ventilation 
they will flow on the lower places like water making a dangerous air gas, and some time 
later a lighted match will finish the job. Various instances of this kind are reported by 
Sir Boverton Redwood and Dr. Du Pre in Redwood’s splendid treatise on Petroleum. 



38 




























































SHOULD PETROLEUM STORAGE TANKS HAVE SPECIAL METALLIC 
GROUNDINGS FOR LIGHTNING PROTECTION? 


The answer to this question is 


NO. 


This foolish question would not appear here only for the fact that metallic groundings 
to the tanks are generally recommended as a prime necessity. The recommendation may 
be well intentioned, but better knowledge of tank conditions and the nature of lightning 
discharges would deal with vital facts and never recommend anything of the kind. 


To drill holes in the tank wall and connect to earth with a few fence wires or any¬ 
thing else is absurd in view of the knowledge that a half acre of metallic tank surface 
is already in the soil in addition to miles of heavy pipe line in the earth and attached to 
the tank. 


There is nothing on earth so well grounded as a petroleum storage tank, and it can 
be demonstrated experimentally there would be less danger to a tank if it was not so 
well grounded. 

When the earth’s electrical field is discharged the pipe lines attached to the tank 
cause a greater and more sudden electrical variation on the tank roof than could be other¬ 
wise, Fig. 1, and the greater this variation the more intense the electro static sparking on 
the roof. 

A 55,000 barrel tank near Ranger, Texas, was burned through lightning causes in 
May, 1920. This tank was sitting in a pond of water at the time and the whole country 
flooded, pipe lines and all. Could anything be better grounded? 

We may here observe, of the hundreds of thousands of steel petroleum storage tanks 
set in masonry in the cities of the United States and elsewhere, we have no record of a 
lightning loss or damage in a single instance and they have no metallic groundings 
whatever. 

With this knowledge in mind who would challenge the assertion that field storage 
tanks, if they could be arranged the same way, would be exactly as safe from lightning 
if their lids were put on properly. 

What the petroleum producers need is knowledge of their tank conditions, based upon 
adequate facts, then treat these conditions intelligently and the tank troubles will end. 


39 



The Dangerous Petroleum Fractions 


An Interesting Petroleum Table 


1 

PETROLEUM 

MEMBERS 

2 

NUMBER 
OF ATOMS 
IN MOLECULES 

3 

RELATIVE 
SUES OF 
MOLECULES 

4 

REIAT1VE 
WEIGHT 
TO AIR 

s 

BOILING 

POINT 

FAHR- 

METHANE 

C H« 

O 

Vz 

- 263° 

ETHANE 

Cz H& 

O 

1 

- 135° 

PROPANE 

C 3 H8 

O 

P/2 

- 49° 

BUTANE 

C* H 10 

O 

2 

+ 32° 

PENTANE 

C 5 Hl2 

O 

2 J /a 

98 

HEXANE 

Cs H» 

O 

3 

156° 

HEPTANE 

C 7 Hie 

O 

3 Vi 

208° 

OCTANE 

C8 Hl8 

O 

4 

256° 

NONANE 

C 9 H 20 

O 

A Yz 

300° 

DECANE 

C.o Hai 

O 

5 

343° 

UNDECANE 

C„ H 24 

O 

5 V& 

381° 

DODECANE 

Cl2 H 26 

O 

6 

417° 

TRIDECANE 

Cl3 H 28 

O 

6Vz 

435° 

TETRADECANE 

Cl4 H 30 

O 

7 

485° 

PENTADECANE 

Cl5 H 32 

O 

7Vz 

518° 

HEXADECANE 

Cl6 H34 

O 

8 

.549° 




Gases at 

> ORDINARY 
TEMPERATURES 


Gasoline 


Kerosene 


j 


Fig. 14 

This is a very instructive table. 

Look it over carefully in advance. 

In column 3, “Sizes,” is used for Masses. 
The text will explain it in detail. 


40 





























Lightning and Petroleum Storage Tanks 

We have told you about the discharge of the Earth’s Electrical Field and its serious 
relation to certain classes of petroleum storage tanks. The problems we have tried to 
explain have been worked out scientifically in field and laboratory and we hope you have 
found them interesting and instructive. Tha following story will tell you some interest¬ 
ing things about petroleum and things that have a direct bearing on the burning of the 
tanks. 

THE CONSTITUTION OF CRUDE PETROLEUM 

- Crude Petroleum is a mixture of about thirty-two different kinds of hvdro-carbon com¬ 
pounds and that means—it gives off about thirty-two different kinds of inflammable 
gases. 

The first sixteen of these various hydro-carbon factors are all we need to consider and 
we give their names and some of their characteristics in the very interesting table, Fig. 
14, which we shall proceed to explain. 

The first four members of our table are exceedingly volatile under any weather con¬ 
ditions and seldom more than a trace to a small percent of them ever reach the storage 
tank. 

The Gasoline Group comes next. These embrace from three to six of the next 
lighter members and together with whatever of the first four may be held in solution 
are the chief tank burners. 

The Kerosene family include the other members of our table. The vapors from kero¬ 
sene are twice as heavy as those from gasoline, and so do not vaporize nor diffuse as 
rapidly. The lightning hazard is not as great as in gasoline, but very dangerous condi¬ 
tions can be created with the heavy vapors of Kerosene. 

The other sixteen members not named make lubricating oils, vaseline and greases and 
need not enter into our considerations, for lightning damage due to these fractions is very 
remote. 

The second column shows the number of atoms of carbon and hydrogen which unite 
to make a molecule of the member it represents. This column should be thoughtfully 
compared with the relative sizes of the molecules in column three, for it is trying to tell 
you something you should know in order that you may reason why some of the vapors 
of crude petroleum are heavier than others. 

The third column shows the relative sizes of the molecules of the different petroleum 
members given and not their real sizes, for the largest molecules are not visible in any 
microscope. 

A molecule is the smallest conceivable particle of any substance, and when matter is 
in liquid form, as in crude petroleum, its molecules flow through and among each other 
near together, while in gaseous form they are relatively far apart, for a cubic inch of 
liquid petroleum will make a cubic foot of gas, more or less, dependent on which member 
we may be considering. 

There is a law—Avogaclro’s Law—governing all gases of every kind, which states, 
“Equal numbers of molecules will occupy equal volumes of space regardless of the sizes 


41 


of the molecules.” By looking down column three of our table, with this law in mind, 
it is easy to reason why some petroleum vapors are heavier than others, for any number 
of large molecules should be heavier than any equal number of small ones, and they are. 
This knowledge is simple and interesting and shows an intelligent relation of the differ¬ 
ent members with their places in the columns of our table. 

Observe the weights and boiling points of the various members in connection with the 
relative sizes of their molecules and this will enable us to think more intelligently as we 
proceed, for in this problem of tank protection we need as much knowledge and do as 
little guess work as possible. 

The fourth column compares the weights of the various petroleum gases with air. 
The second member, Ethane, in gas form is the same weight as air, while Methane gas is 
only half as heavy, and all of the others are heavier than air and much heavier, but this 
is what you would expect after looking down columns two and three. Where there 
is no air circulation the heavier gases may lie around in pockets for some time or flow 
along the lower surfaces like water and they can be poured from one dish into another, 
so we can see how it is possible to arrange conditions so the heavier vapors might be the 
more dangerous, although this is very improbable outside of confinement, or in free air, 
and our tank menaces are seldom associated with that class. 

The fifth column discovers the causes of our tank troubles. This column shows the 
temperature at which each member, if separated from the others, will rapidly become 
gas. It should be observed, however, these boiling points only hold true when the mem¬ 
bers are separated from each other and not when mixed together. Pure Methane liquid 
in a vessel would boil and become gas at 263 degrees below zero, Fahrenheit. In this 
respect it is not unlike liquid air, but when mixed with the other petroleum members in 
a large tank a small percent of it may be held in solution for some time at a temperature 
far above its own boiling point. The same is true of Ethane, Propane and Butane, but 
all of these attempt to get out as quickly as possible, especially on a warm day, for 
they are all gases and not liquids at natural temperatures. 

It follows, therefore, that new oils are richer in the lighter hydro-carbon members and 
consequently a more serious lightning hazard than oils that have been exposed to evap¬ 
oration for a longer period of time. 

INFLAMMABLE CONDITIONS AND WHAT HAPPENS AT TANKS 

These hydro-carbon gases are neither inflammable nor explosive unless mixed with 
air, and the ratio of this mixture is very interesting, especially if lightning is in the neigh¬ 
borhood. One per cent of petroleum gas mixed with air is not inflammable. One and one- 
half per cent will burn feebly. Two per cent to five per cent is sharply explosive, and 
more than six per cent is too rich in hydro-carbons to be explosive, but is, of course, in¬ 
flammable where it blends into a thinner mixture. When air gas within a tank is too 
rich to explode it might burn around the edges of the roof for some time until it had 
burned an opening sufficient to let in enough air to dilute the mixture, when away might 
go to the top of the tank. 


42 


In warm weather the mixture of gases within a tank which contains a good per cent 
of the lighter fractions, is always explosive or inflammable, but these gases are seldom if 
ever either explosive or inflammable at much distance apart from a tank, as we shall 
presently show, and the solution of our fine problem is related only to the vapors in 
immediate contact with the tank and no where else. 

The preconceived opinion that tank fires result from inflammable vapors high in the 
air is not founded on intelligent calculation. The factors of evaporation and diffusion are 
not scientifically considered with reference to a free atmosphere such as surrounds a stor¬ 
age tank, but rather with conditions such as might exist within an enclosure, and no suc¬ 
cessful system of tank protection can be established on such erroneous principles. 

A RULE AND A PROBLEM 

Here is a simple little rule which will help to square us with the facts. “A cubic inch 
of volatile petroleum will make a cubic foot of gas, and this cubic foot of gas will 
render 70 cubic feet of air slightly combustible.” With this rule we may do some scien¬ 
tific calculation and less guess work, so let us try it on a practical problem. 

Problem:—A 55,000 barrel tank during the heated season in Oklahoma will evaporate 
about fourteen barrels of volatile petroleum a day. How much confined air would that 
make inflammable? 

Solution:—Fourteen barrels of petroleum are equal to 141,428 cubic inches and that 
multiplied by 70 equals almost 10,000,000, which would represent the maximum number 
of cubic feet of inflammable air it could produce. This is equal to an enclosure 215 feet 
square and 215 high, or it would equal the volume of a cylinder the diameter of which 
equals that of the tank retaining earth wall and 200 feet high. 

This, of course, applies to confined air such as would be in a room with no open doors 
or windows, as the law of diffusion would not permit gases to collect in this way in a 
free atmosphere, even if there was not a breath of wind. 

Any air movement less than three miles an hour is a calm. Suppose, however, the 
wind should be blowing only one mile an hour, in that event the first vapors from our 
fourteen barrels would be in the adjoining county before the last vapors left the tank 
and the rest would be scattered all along the way and diffused in every direction. But 
the weather bureau tells me the average velocity of the wind in Oklahoma is 13 miles 
an hour and more during thunder storms, so what would that do to our vapors as they 
left the tank and where in the light of reason could you find a one and one-half per 
cent, or inflammable mixture very far from the tank? 

THE ARDMORE DISASTER 

The Ardmore Disaster in September, 1915, was caused by the escape of more than 
500,000 cubic feet of vapor and spray within a few minutes, and all of this from one hole 
in a tank car. But that is more vapor than ordinarily would escape from a 55,000 barrel 


43 


tank in a week, and if this had taken an hour to escape, instead of a few minutes, there 
would have been no disaster at Ardmore, as the vapors would have been scattered over 
many miles instead of a few blocks. 


Flowing wells give off vapors much more profusely than do storage tanks and might 
create an inflammable region for some rods on a calm day, but never so far on a windy 
day because of more rapid diffusion. 

If all of the vapors that ordinarily escape from a flowing well in six hours could 
be released in a few minutes that would create a condition in its locality akin to the con¬ 
dition at Ardmore when 125 barrels of casinghead suddenly vaporized from a transit car 
when the pressure was released. Nothing approaching this, however, is possible in the 
evaporation from a storage tank in free air under any conditions, and all such thoughts 
should be dismissed. 


VAPOR TESTS AT TANKS 

In August, 1912, the writer tested many samples of air gas from the region of very 
volatile petroleum in storage and was unable to get an inflammable mixture six inches 
outside of any tank at any place on any of these days. This does not means there are 
never inflammable vapors outside of a tank for a much greater distance, for there surely 
are, but under any conditions the inflammable range is far within the limits of popular 
belief. 


PETROLEUM GAS A VERY POOR CONDUCTOR OF ELECTRICITY 

Gases of every kind under normal conditions are very poor conductors of electricity 
but none are poorer in this quality than petroleum. 


The author finds in laboratory tests that a lightning discharge will ignore an ascend¬ 
ing stream of petroleum vapor and make a path between the experimental cloud and tank 
quite apart from the vapor stream. 


A burning petroleum tank, however, endangers neighboring tanks because flame is 
a very good conductor of electricity and ionizes the air to a great height. This might 
cause lightning discharges there that otherwise would not occur, which would cause electro 
static sparking on neighboring tanks with wooden roofs or roofs covered with loose sheet 
metal. 


A burning petroleum tank could hardly cause a fire in a neighbor tank from its own 
flames unless the flames could reach the neighbor, because of the rapid diffusion of petro¬ 
leum gases in free air. 


44 


EPITOME 

We may summarize the foregoing in the following fourteen points: 


ONE 

All lightning tank fires are in one way or another due to tank roof conditions. 
Knowledge of these conditions is essential to tank protection. 


TWO 

The electrical charge of that part of the earth electrical field occupied by the tank 
is all on the upper surface of the tank roof. This charge is gradually acquired by the 
inductive action of a growing charge on a cloud and bound by the influence of the electri¬ 
fied cloud till released. 

THREE 

A lightning flash is the result of the discharge of the electricity from both the cloud 
and the earth electrical field. This discharge suddenly releases the bound charge on all 
tank roofs at that instant. The danger to the tanks is dependent on how this released 
charge gets off the roofs. 


FOUR 

The danger to wooden roof tanks or a roof covered with sheet metal is in the loose 
contacts of the various sheets of metal and the imperfect electrical contacts of the roof 
to the tank. Electrostatic sparks are liable to occur at loose metallic contacts when the 
bound charge on the roof is released by a lightning discharge at the tank or in the vicin¬ 
ity. 


FIVE 

The secret of safety in steel roofed tanks is the well riveted sections of the roofs and 
the well riveted roof to their tanks. This permits all parts of the roofs to discharge with¬ 
out electrical resistance. A properly connected steel roof with closed winch box should 
make a tank as free from lightning danger as is a railway car or a steel structural build¬ 
ing. 


SIX 

A tank should be kept free from line wires as these greatly increase the danger zone. 
This is especially true of a tank with loose’y connected sheet metal sections on the roof 
and poor electrical contact of the roof with the tank. A tank roof should also be kept 
free from vent pipes of any description, extending upwards, as such vent pipes or chim¬ 
neys invite an electrical discharge at the very spot where the inflammable vapors are 
escaping. 


SEVEN 

The extended metallic pipe connections of a storage tank throughout the earth elec¬ 
trical field intensify electrostatic sparking at a tank roof, at the instant of a lightning 


45 


discharge anywhere within that field. Additional metallic groundings of the tank could 
do little extra harm and have no beneficial results whatever. 


EIGHT 

Sealing of tank roofs should be governed by scientific knowledge of the causes of 
tank fires, otherwise the tank is endangered. 

NINE 

The richer the air gas within a tank the greater the fire hazard from electrostatic 
sparks at the edge or on top of the roof. Sparks that could ignite some tanks could 
not ignite some others, because of the gas mixture, but the stronger the spark, the surer 
the fire in either case. 


TEN 

The region of inflammable air gas surrounding any storage tank is limited to a 
very narrow zone and the danger from electrostatic sparks is outside and in contact with 
the tank, as sparks cannot occur within a tank nor away from its exterior surface. A di¬ 
rect lightning stroke at a tank, however, would be a dangerous thing within this narrow 
zone. 


ELEVEN 

An open winch box on a tank roof establishes a serious condition around the region 
of the head of the stair railing during local thunder storms. This is especially true of a 
tank that is tightly sealed. No system of protection could save a tank under such condi¬ 
tions if a flash of lightning occurred at the top of the stair railing. 


TWELVE 

A storage tank is specially subject to St. Elmo’s fire because of its extensive metallic 
earth connections. Laboratory experiments prove beyond any question that wooden roofed 
tanks could take fire at their roof connections from this cause. Steel roof tanks would 
not be affected. 


THIRTEEN 

Unless the metallic reinforcing and other metallic structural work of a concrete reser¬ 
voir are properly connected together' and to earth before the concrete is shot on, little could 
be done afterwards to protect the reservoir from electro static sparks. It should be a safe 
container if properly connected. 


FOURTEEN 

The West Dodd Tank Protection System is designed to neutralize every sparking 
possibility on the tank roof. This is accomplished by bringing every sheet of metal on 
the roof into perfect electrical union with the system, which has electrical connection to 
the tank rim every few feet. It would be impossible for an electrical charge to leave the 
roof except through the system and the roof is thus discharged without resistance, the 
same as is a steel roofed tank. 


46 


Special Scientific Demonstration 

The author is the originator of the thunder storm machine and can demonstrate elec¬ 
trically. 

EVERY PRINCIPLE ENUMERATED IN THIS BOOK TOGETHER WITH THE 
DISCHARGE OF THE EARTH’S ELECTRICAL FIELD 

Showing Electro Static sparking on improperly arranged tank roofs situated within 
the electrified earth area. 

PIPE LINES 

Showing the serious electric influence pipe lines extending into the earth’s electrical 
held have upon the tanks to which they are connected at the instant of a lightning dis¬ 
charge anywhere near these lines. 

SAINT ELMO’S FIRE 

Showing the Brush Electrical Discharge from a tank under the influence of a charged 
cloud and a possible cause for some tank fires without lightning resulting at the instant. 

THE OPEN WINCH BOX 

Showing a direct lightning flash at the stair railing and setting the tank on fire from 
the gases escaping from the winch box. / 

NO BRANCH LIGHTNING 

Showing an electric condenser will only discharge in one place within a region con¬ 
nected up with pipe lines such as would be at any tank farm. 

THE WEST DODD PROTECTION SYSTEM 

Showing how and why it will prevent electro static sparking on a tank roof and the 
necessity for proper diagnosis to determine tank conditions. 

REMARKS 


The Scientific principles mentioned in this book have a wonderful meaning to the na¬ 
tion as well as to the petroleum industry and should not be conjured and discounted in 
the field by a novice who has little or no knowledge of the nature of electro static dis¬ 
charges. 

These principles as related to petroleum storage tanks have been developed and 
worked out by the author during years of study in the field and in the laboratory. 

Every feature associated with thank protection is scientific and special in the highest 
degree and not to be juggled by pseudo scientific men incompetent to judge of tank 
dangers during lightning discharges. 

The author is ever ready and willing to discuss, demonstrate and elucidate these prin¬ 
ciples with scientific men or any who may be sincerely interested, free of expense and 
without obligation. 

Address: The West Dodd Tank Protection Co., Des Moines, Iowa. 


47 


REFERENCES 

The following references may be interesting to any who seek scientific knowledge 
along some of the lines we have endeavored to simplify: 

“THE DISCHARGE OF THE EARTH ELECTRICAL FIELD” 

Consult “On the Sign and Magnitude of Electric Discharges in Lightning Flashes,” 
by C. T. R. Wilson, M. A., F. R. S., observer in Meteorological Physics at the Solar Ob¬ 
servatory, Cambridge, England, fully discussed in the Proceedings of the Royal Society 
A Vol. 92, 1916, pages 555 to 574. Also in bulletin form. 

This master scientist discovered and describes a means to determine the volt meter 
variations at any place within the earth electrical field at the instant of a lightning dis¬ 
charge, whether near or far. 

Can be obtained through the Scientific American or D. Van Nostrand Co., 25 Park 
Place, New York. 

“THE BRUSH ELECTRICAL DISCHARGE” 

See “Experimental Researches on Electricity,” Vol. 1, pages 454 to 472, by Michael 
Farady. 

Also “Elementary Lesson in Electricity and Magnetism,” pages 298 to 300, by Syl- 
vanus Thompson. 

CONCERNING “IONIZATION OF GASES” 

Consult “Electrons,” by Sir Oliver Lodge. 

Also “The Discharge of Electricity Through Gases,” by Prof. J. J. Thompson. 

DIFFUSION OF GASES 

See Avogadro’s Law. Found in any good work in Physics. 

Also see “The Kenetic Theory of Gases,” chapter 3, part 2, by C. E. Meyers. Also 
A. D. Risteen’s “Molecules.” 


PETROLEUM GASES 

Consult Boverton Redwood’s “Treatise on Petroleum,” Vol. 2. 

This work is in three volumes and is very complete. 

Questions relative to Lightning Protection to any kind of Property cheerfully and 
freely answered. 

Address, WEST DODD, Des Moines, Iowa. 

48 


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